The truck was travelling in the eastbound lanes of Hwy. 401 at Hwy. 115 just after 12 a.m. ET when the driver lost control, smashing into a bridge rail and sliding off the road into the adjacent ditch, police said.
The collision caused the tanks to overturn, and one tank spilled the entirety of it's content.
"The smell of diesel fuel is in the air," said OPP Sgt. Kerry Schmidt. "I haven't experienced a fuel spill like this that I can remember."
Crews from the Ministry of Environment are trying to contain the spill, as Wilmont Creek flows just east of where the truck spilled the fuel. Schmidt said diesel fuel could be scene pooling at the side of the road and was seemingly seeping into the ground.
The truck has been pulled out of the ditch, but for several hours all eastbound lanes of Hwy. 401 were closed at the scene of the incident. One lane has since reopened to traffic.
The driver sustained minor injuries. Schmidt said the man is charged with one count of careless driving.
Currently officials are not concerned for public safety, but the cleanup could take several hours, Schmidt said.